DeFi Smart Contract Vulnerabilities Audit Guide

Here are three specific DeFi smart contract vulnerabilities suitable for an audit report, detailed with technical context, impact, and mitigation strategies.

1. Reentrancy Vulnerability in State-Dependent Functions

Vulnerability Description:
A reentrancy vulnerability occurs when a smart contract calls an external contract before completing its state changes. If the external contract is malicious, it can re-enter the vulnerable function before the state is updated, allowing an attacker to drain funds or manipulate logic. This is particularly critical in functions that handle token transfers or balance updates.

Specific Example (Solidity):
Consider a staking contract with a withdraw() function:

solidity
function withdraw(uint256 amount) external {
    require(balances[msg.sender] >= amount, "Insufficient balance");

    // Vulnerable: External call BEFORE state update
    (bool success, ) = msg.sender.call{value: amount}("");
    require(success